1. Field of the Invention
This invention relates to an endoscope pipeline controlling apparatus for controlling respective air and water feeding and sucking pipelines
2. Description of the Related Art
Recently, an endoscope has been developed whereby, an elongate insertable section inserted into a body cavity allows organs within the body cavity to be observed and, as required, with a treating instrument inserted through a treating instrument channel allows various therapeutic treatments to be made is extensively utilized and is used not only medically but also industrially to observe and inspect the interiors of such objects as boilers, mechanical and chemical plant pipes or machines.
Further, various electronic endoscopes have been developed in which a solid state imaging device, such as a charge coupled device (CCD), is used as an imaging means in the tip part of an insertable section.
Now, in the case where an endoscope or, particularly, a medical endoscope, is inserted into a body cavity, obstructions such as a body liquid will be deposited on the observing window and will obstruct the observation and, therefore, the observing window will have to be cleaned. Therefore, generally, in an endoscope, the observing window is cleaned by feeding air and water from a nozzle provided in the observing window through an air and water feeding pipeline. Also, in order to observe even the smallest details of the part to be inspected, it is necessary to feed air into the body cavity to separate the body wall and the endoscope tip part from each other.
Therefore, the endoscope is provided with pipelines for feeding and sucking air and water. The air feeding pipeline and water feeding pipeline join with each other on the tip side of the insertable section of the endoscope and communicate with a nozzle opening toward an observing window provided in the tip part. In the case where the observing window is stained with a viscous liquid or dirt, water and air are fed toward the observing window from the above-mentioned nozzle so as to be able to remove the stain.
Therefore, the endoscope apparatus is provided with a controlling means for controlling the switching of the above-mentioned feeding and sucking of air and water. For this controlling means, a mechanical controlling method is already generally used wherein a switching valve provided in an operating section of an endoscope is operated directly with fingers, and an electric controlling method is also commonly used wherein, as shown in the publication of Japanese Patent Application Laid Open No. 75131/1981, a switch is provided in an operating section of an endoscope and is operated with fingers to control electromagnetic valves provided in respective pipelines within a photoelectric source apparatus. As compared with the mechanical controlling method, in the above-mentioned electric method, the automatic feeding of air after the feeding of water and the automatic sucking after the feeding of water are possible so that not only the water evacuation of the pipeline can be improved, but it is also not necessary to provide a switching valve having a complicated structure and low in washability in the pipeline formed within the endoscope and therefore this method is high in washability, and is considered sanitary.
Now, in an endoscope in which respective pipelines for feeding and sucking air and water are controlled by the electric method, a controlling apparatus consisting of electromagnetic valves or the like is required. This controlling apparatus has been provided integrally with a light source apparatus and therefore has become very expensive. Therefore, in case a user having a mechanical controlling method light source apparatus and endoscope wants to buy and use an electric controlling method endoscope, he will have to buy a light source apparatus integral with a controlling apparatus consisting of electromagnetic valves or the like.
Also, in endoscopes of the prior art, as the endoscope is inserted into the body cavity within which the internal pressure is higher than the atmospheric pressure, in case the endoscope is pulled out of the body cavity, the obstructions deposited near the nozzle may flow back into the nozzle. When the endoscope is left as it is or is dipped into a chemical liquid, the obstructions and dirt may coagulate within the nozzle or air and water feeding pipelines. If the nozzle and the like are clogged, the observing window will be no longer able to be washed, and it will be very difficult to remove the coagulated dirt and the endoscope observation will be likely to be greatly obstructed.
Further, as described above, in the endoscope, in order to make the endoscope observation easy, air is constantly fed through an air feeding pipeline to inflate the body cavity wall. So that the body cavity wall may not be varied or damaged by the excess air feed in such case, according to the related art mentioned in the publication of Japanese Patent Application Laid Open No. 22243/1989, the excess air feed is prevented and the pressure within the body cavity is always kept constant lest the pressure within the body cavity be reduced in excess by the sucking operation.
Now, the endoscope inspection applying position can be of such comparatively thick position as a body wall or at such a very thin position as a membrane. In spite of such differences in the body cavity tissue, the air feeding pressure, water feeding pressure and sucking pressure are set to be constant. The above-mentioned pressures are set to be rather low to secure the safety in the very thin body wall position, that is, to prevent a body cavity rupture or mucous membrane adsorption. However, in case a thick body wall position is to be inspected with such a low setting, even if air is fed to secure the visual field, the body cavity interior will not be easily inflated and, when the inspection ends, even in case the fed air is sucked, it will not be easily sucked and the inspection time will be unduly long.
On the other hand, various kinds of endoscopes are prepared in conformity with the applying positions of the examined body to be observed, and the respective inserted position diameters, optical systems, pipeline inside diameters and pipeline lengths are different.
Further, in the endoscope in which the pipeline is controlled by the electric method shown in the above described Japanese Patent Application Laid Open No. 75131/1981, in order to improve the evacuation of water droplets on the objective lens surface after feeding water, as shown in the publication of Japanese Patent Application Laid Open No. 220833/198, air is automatically fed after feeding water or, as shown in the publication of Japanese Patent Application Laid Open No. 277931/1987, the air feeding pipeline is automatically made to vent to the atmosphere after feeding water.
Now, in the endoscope in which, as shown in FIG. 27, the air feeding pipeline 33 and water feeding pipeline 34 join with each other on the insertable section tip side and communicate with the nozzle 36 through the air and water feeding joint pipeline 35, when water is fed to the water feeding pipeline 2 from the state shown in FIG. 27(A), as shown in FIG. 27(B), the pressure of the pump which is a water feeding means, that is, the water feeding pressure will compress the gas within the air feeding pipeline and therefore the washing water from the joining point 35 will flow back into the air feeding pipeline 33. When the water feeding is stopped, the above-mentioned compressed air will expand and will push out the washing water which has flowed back into the air feeding pipeline 33, as shown in FIG. 27(C). However, even if the washing water thus having flowed back into the air feeding pipeline 33 is pushed out, water drops will remain on the inside wall of the air feeding pipeline 33, as shown in FIG. 27(D). Even if air is fed to blow away the water drops on the observing window after feeding water, as shown in FIG. 27(E), the remaining water drops will fly out successively. Thus, the water drops on the observing window will not be easily removed. In the case of the control by making the air feeding pipeline 33 leak to the atmosphere after feeding water, as shown in FIG. 27(C'), the water having flowed back into the above-mentioned air feeding pipeline 33 will remain as it is. If feeding air is repeated several times, water will be likely to spread out of the leaking pipeline.
Also, as described above, the air feeding pipeline and water feeding pipeline of the endoscope join with each other on the tip side of the insertable section and communicate with the nozzle opening toward the objective lens provided in the tip part so that, in case the objective lens is stained by the mucous liquid and dirt within the body cavity, air and water will be fed toward the objective lens from the above-mentioned lens so as to be able to remove the stain. Further, the endoscope has a function of automatically sucking after feeding water to improve the water cut of the water drops deposited by the water feeding on the objective lens surface.
However, in the above-mentioned conventional endoscope air and water feeding and sucking apparatus, particularly one in which sucking occurs automatically after feeding water, a comparatively high suction will be required in order to suck and remove the water drops on the objective lens with a momentary suction after feeding water. However, the sucker usually used for the endoscope sucks the mucous liquid or the like obstructing the observation in the endoscope inspection and is set to be under such pressure so as to not damage the tissue even if the body cavity wall or the like is sucked by mistake during the inspection.
Therefore, the suction pump used for suction shall be a safe pump low in the closing pressure and shall make the sucking pipeline on the sucker side leak to the atmosphere also from the suction controlling valve when no suction is made in order to increase safety. Even if such a sucking means low in suction is used to momentarily suck after feeding air, as just after the leaking state, the sucking pressure will not be transmitted to the channel opening provided at the tip of the insertable section of the endoscope. It has been difficult to suck the water drops on the objective lens.
Further in the above-described endoscope apparatus, in feeding air and water by one pump, at the time of feeding water, if spray water is fed by opening both the air feeding pipeline and the water feeding pipeline, in case the operator carelessly tumbles the water feeding tank during the inspection, a liquid surface will be made in the opening 5 of the water feeding pipeline and air and washing liquid may be simultaneously sucked up. Then, an air layer and a washing liquid layer will be alternately formed within the water feeding pipeline. In such a state, the pipeline resistance of the water feeding pipeline will become so large that, in case spray water is to be fed again, the entire pressure of the pump will escape to the air feeding pipeline side having a lower pipeline resistance than the water feeding pipeline, and water will no longer come out of the nozzle. In the case of such a state, the inspection will be stopped at once and the spray water feeding control will have to be switched over to the ordinary water feeding control. In the above, resumption of feed water becomes complicated, long and inflicts pain upon the patient.